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From: phil@diablo.amd.com
Newsgroups: sci.electronics
Subject: battery chargers
Message-ID: <28220@amdcad.AMD.COM>
Date: 1 Dec 89 18:46:44 GMT
Sender: news@amdcad.AMD.COM
Reply-To: phil@diablo.amd.com ()
Organization: Advanced Micro Devices, Inc. Sunnyvale CA
Lines: 22


I just found a source of 12 V 6 AH sealed no maintenance lead acid
batteries for $10 each. They seem to have a lot of applications (house
burglar alarm, CB radio power, video camera and lights, etc) so I am
looking for some advice on what a charger needs to do. What is an
appropriate fast charge rate? Is it ok to trickle charge them in a
burglar alarm application? What does the discharge curve look like?
How should a fast charger know when to turn off? Do lead acids have
the memory problems of NiCads? Is it ok to leave them flat? What is
the best condition to store them in? 

And out of curiousity, how do the corresponding NiCad systems work?
I'm used to overnight, 1/10 rate chargers but lately I've seen a
Norelco cordless shaver that magically recharges in about an hour, as
well as a Makita 9.6V systems that recharges in about the same time. I
am told the Makita just dumps energy into the battery and stops when
it gets hot; it certainly does get hot. The cordless shaver doesn't
seem to get hot but it might be doing so inside, I think it stores a
lot less energy. 
--
Phil Ngai, phil@diablo.amd.com		{uunet,decwrl,ucbvax}!amdcad!phil
AT&T Unix System V.4: Berkeley Unix for 386 PCs!


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